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Research: how to build a meta predicate to perform this detection

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This commit is contained in:
Fischlurch 2017-11-19 00:35:10 +01:00
parent 2345d76138
commit 8f865183e3
1 changed files with 55 additions and 11 deletions
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66
research/try.cpp
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@ -45,14 +45,15 @@ typedef unsigned int uint;
#include "lib/format-cout.hpp"
#include "lib/format-util.hpp"
//#include "lib/meta/function.hpp"
#include "lib/meta/duck-detector.hpp"
#include "lib/test/test-helper.hpp"
#include <functional>
#include <utility>
#include <string>
//using lib::meta::_Fun;
using lib::meta::No_t;
using lib::meta::Yes_t;
using lib::test::showSizeof;
using std::function;
@ -65,38 +66,81 @@ using std::string;
#define SHOW_TYPE(_TY_) \
cout << "typeof( " << STRINGIFY(_TY_) << " )= " << lib::meta::typeStr<_TY_>() <<endl;
#define SHOW_EXPR(_XX_) \
cout << "Probe " << STRINGIFY(_XX_) << " ? = " << _XX_ <<endl;
int
void
fun1 (long)
{
cout << "long FUN" <<endl;
}
int
fun1 (string, long)
{
cout << "string FUN" <<endl;
return 12;
}
void
fun2 ()
fun1 ()
{
cout << "NO FUN" <<endl;
}
template<typename X, typename SEL =decltype(fun(std::declval<X>()))>
struct Probe
class Cheesy
{ };
class Fishy
{
friend void fun1 (Fishy&);
};
#define META_DETECT_EXTENSION_POINT(_FUN_) \
template<typename TY> \
class HasExtensionPoint_##_FUN_ \
{ \
template<typename X, \
typename SEL = decltype( _FUN_(std::declval<X>()))>\
struct Probe \
{ }; \
\
template<class X> \
static Yes_t check(Probe<X> * ); \
template<class> \
static No_t check(...); \
\
public: \
static const bool value = (sizeof(Yes_t)==sizeof(check<TY>(0))); \
};
META_DETECT_EXTENSION_POINT (fun)
META_DETECT_EXTENSION_POINT (fun1)
int
main (int, char**)
{
fun1 (23);
fun2 ();
fun1 ();
using Ty1 = decltype (fun1(12));
using Ty2 = decltype (fun2());
SHOW_EXPR ( HasExtensionPoint_fun<long>::value );
SHOW_EXPR ( HasExtensionPoint_fun1<long>::value );
SHOW_EXPR ( HasExtensionPoint_fun1<long&>::value );
SHOW_EXPR ( HasExtensionPoint_fun1<long&&>::value );
SHOW_EXPR ( HasExtensionPoint_fun1<char>::value );
SHOW_EXPR ( HasExtensionPoint_fun1<char&>::value );
SHOW_EXPR ( HasExtensionPoint_fun1<char&&>::value );
SHOW_EXPR ( HasExtensionPoint_fun1<string>::value );
SHOW_EXPR ( HasExtensionPoint_fun1<void>::value );
cout << "siz-1="<< sizeof(Ty1)<<endl;
cout << "siz-2="<< sizeof(Ty2)<<endl;
SHOW_EXPR ( HasExtensionPoint_fun1<Cheesy>::value );
SHOW_EXPR ( HasExtensionPoint_fun1<Fishy>::value );
SHOW_EXPR ( HasExtensionPoint_fun1<Fishy&>::value );
SHOW_EXPR ( HasExtensionPoint_fun1<Fishy&&>::value );
SHOW_EXPR ( HasExtensionPoint_fun1<Fishy const&>::value );
cout << "\n.gulp.\n";